1. Field of the Invention
This invention relates to an engine unit, and more particularly to an engine unit having a cylinder block and a lower case fixed to the lower portion of the cylinder block.
2. Description of the Related Art
Recently large-capacity engines are manufactured by die-casting in aluminum. Hence, they are light and mass-produced. It is desired that these engines make as less noise as possible and withstand as great a load as possible. In particular, a V-type engine must withstand a great oblique load. The bearing caps used in the V-type engine are therefore made of cast iron. They are fastened by bolts to the crank journals of a cylinder block.
There has been known cylinder blocks of a longskirt type in which bearing caps are connected together by means of beams or bed plates or fastened to the skirts by side bolts, so as to prevent the bearing caps from inclining and to enhance their rigidity. However, the long-skirt type cylinder block is rather massive, making it difficult to laying out a starter, an oil filter, a 4WD transmission, and the like, neatly within a limited space. Further, the rigidity of the caps is insufficient and inclination of the caps cannot be suppressed as much as desired.
In order to eliminate the problems resulting from the long-skirt type cylinder block, a short-skirt type cylinder block having a lower case has been developed. With this cylinder block, bearing caps made of cast iron are set firm in the lower case as the lower case is diecast in aluminum In this case, the bearing caps are sufficiently rigid indeed, but it takes much time to cast the bearing caps in the lower case, inevitably making it difficult to mass-produce engines.